This invention relates to a cannula or sheath and particularly to a cannula useful with angiographic catheters.
In certain angiographic studies, the angiographer uses the Desilets-Hoffman procedure to do a multiple study. In this procedure, the angiographer obtains access to a patient""s blood vessel by inserting a hollow needle through the skin and into the lumen of the blood vessel. A guide wire is passed through the needle and advanced through the artery or vein into the organ to be studied. The needle is removed leaving the guide wire in the organ. A cannula and dilator are advanced over the wire into the vessel and the dilator is removed along the guide wire. The angiographer then conducts the multiple studies by inserting various types of catheters into the vessel through the cannula or sheath. In order to avoid excessive bleeding and to insure against the possibility of an air embolism, this technique requires occlusion of the passage through the cannula during catheter changes.
One method of obtaining the required occlusion is to position a valve body formed from a pliable material in the passageway of the cannula. Such valve bodies are shown for instance in U.S. Pat. No. 4,000,739 to Stevens, U.S. Pat. No. 4,430,081 to Timmermans, U.S. Pat. No. 4,610,665 to Matsumoto et al., U.S. Pat. No. 5,006,113 to Fischer and International Publication Number WO 91/10459 to Savage et al. In each of these patents, one or more disk-like gaskets are mounted in the cannula passage. The disk-like gaskets or valve bodies include an opening therethrough which is biased to a closed position when no catheter is present in order to prevent an air embolism from occurring by air being drawn into the patient""s vein through the cannula. When a catheter is inserted through the valve body into the passage of the cannula, the valve body conforms to the shape of the outer wall of the catheter, thereby preventing blood flow out of the cannula between the catheter and the valve body.
One embodiment of the present invention concerns a hemostasis cannula that includes a housing. The housing has a passage sized to receive a catheter and an abutting surface. A cap is coupled to the housing, and the cap has at least one internal wall adjacent to the abutting surface. A body is formed from a pliable material, and the body has a first planar face, a second planar face and a peripheral edge separating the faces. The first face includes a slit that extends across the first planar face and defines a slit plane that intersects the peripheral edge at at least one point. The slit extends only partly through the body. The second planar face includes an opening, the opening extending partly through the body, and the slit intersects the opening within the body. The slit and the opening are formed in the body while unstressed before being placed in contact with the internal wall and the abutting surface. The body has a length dimension perpendicular to the slit plane and a width dimension perpendicular to the length dimension. The length dimension is greater than the width dimension. The body is placed so that the internal wall of the cap contacts a portion of the peripheral edge of the body and one of the planar faces of the body contacts the abutting surface of the housing, for compressing the body only in a direction substantially perpendicular to the slit plane in order to maintain a fluid tight seal through the body. The width dimension of the body is chosen such that when the body is compressed within the internal wall, the body expands in the width dimension so that a portion of the peripheral edge of the body does not contact the internal wall of the cap. The portion of the peripheral edge of the body which does not contact the internal wall includes the at least one point at which the slit plane intersects the peripheral edge. At the at least one point at which the slit plane intersects the peripheral edge, no portion of the peripheral edge of the body contacts the internal wall.
Another embodiment of the present invention concerns a hemostasis cannula that includes a housing. The housing has a passage to receive a catheter and an abutting surface. A cap is coupled to the housing, and the cap defines a recess that has at least one internal wall adjacent to the abutting surface. A body is formed from a pliable material and is placed in contact with the internal wall and the abutting surface. The body has a first planar face, a second planar face and a peripheral edge separating the faces. The first face includes a slit extending across the first planar face and defining a slit plane that intersects the peripheral edge at at least one point. The slit extends only partly through the body. The second planar face includes an opening, the opening extending partly through the body. The slit intersects the opening within the body. The slit and the opening are formed in the body while unstressed before being placed in contact with the internal wall and the abutting surface. The body has a length dimension perpendicular to the slit plane and a width dimension perpendicular to the length dimension. The length dimension of the body is greater than a length dimension defined by the internal wall. The width dimension of the body is less than a width dimension defined by the internal wall. When the body is placed into contact with the internal wall, the body is compressed only in a direction substantially perpendicular to the slit plane to maintain a fluid tight seal through the body. At the at least one point at which the peripheral edge is intersected by the slit plane, no portion of the body contacts the internal wall.
A further embodiment concerns a method for making a hemostasis cannula. In the method, a housing that has proximal and distal ends is provided. The housing includes a cap with a recess defined by at least one wall. The housing includes an abutting surface and a passage sized to receive a catheter. The recess has a recess height dimension and a recess width dimension perpendicular to the recess height dimension. A body that is formed from a pliable material is provided. The body has a first planar face, a second planar face and a peripheral edge separating the faces. The first planar face includes a slit that extends only partly through the body and defines a slit plane that intersects the peripheral edge at at least one point. The second planar face includes an opening, the opening extending partly through the body. The slit intersects the opening within the body. The body additionally includes a body height dimension and a body width dimension, which is perpendicular to the body height dimension and parallel to the slit plane. The body height dimension is greater than the recess height dimension, and the body width dimension being less than the recess width dimension. The slit and the opening are formed in the body while unstressed before being received in the recess. The body is received within the recess with the second face directed towards the proximal end of the housing such that the body contacts the wall and the abutting surface. The body is compressed only in a direction substantially perpendicular to the slit plane when the body is received within the recess. At the at least one point at which the peripheral edge is intersected by the slit plane, no portion of the body contacts the wall of the recess.
Another embodiment concerns a hemostasis cannula that includes a housing. The housing defines a passage for receiving a catheter. A cap is coupled to the housing. The cap defines a cap opening to receive the catheter and a cap recess. The cap recess has a height and a width. A valve body is sandwiched in the cap recess between the housing and the cap to seal the passage in the housing. The valve body is formed from a pliable material. The valve body includes a first face that has a slit extending across the first face to define a slit plane. The valve body has a height that is perpendicular to the slit plane. The valve body further includes a second face that defines a valve body opening directed towards the cap opening in the cap. The slit extends only partly through the valve body to intersect the valve body opening within the valve body. A peripheral edge separates the first face from the second face, and the peripheral edge includes a pair of parallel planar surfaces that extend perpendicular with respect to the slit plane. parallel planar surfaces define a width of the valve body that is perpendicular to the height of the valve body. The height of the valve body is greater than the width of the valve body. The height of the valve body is greater than the height of the recess when the valve body is in an uncompressed state. The valve body is compressed within the cap recess to reduce the height of the valve body in order to fit in the cap recess. The width of the valve body is less than the width of the recess when the valve body is compressed within the end cap. The parallel planar surfaces allow the width of the valve body to expand without the parallel planar surfaces contacting the cap when the valve body is compressed in the cap recess. This permits the valve body to compress only in a direction substantially perpendicular to the slit plane to maintain a fluid tight seal through the slit in the valve body.
One object of the present invention is to provide an improved hemostasis cannula.
Another object of the present invention is to provide a method for making an improved hemostasis cannula.
Related objects and advantages of the present invention will be apparent from the following description.